<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function getSumOfArray(arr = []) {
            let sum = 0;
            for (let i = 0; i < arr.length; i++) {
                sum += arr[i];
            }
            return sum;
        }

        let numbers = [1, 2, 3, 4, 5];
        alert('数组元素的和是: ' + getSumOfArray(numbers));
    </script>
</body>
</html>